Q: Engine light Problem

U1900 is a communications failure and the other code is possibly setting simply because the controller (U1900) that is not reporting controls the ABS module. The circuits between the anti-lock brake system (ABS) module, the instrument cluster, the power train control module (PCM) and the trailer brake controller (if equipped) are all on the CAN (controller area network) referred to in this Code (U1900) and all of those will have to be tested. Sometimes, an instrument panel fault causes the code to set. The Factory Service Manual (FSM) sets out a "decision tree" to perform the diagnostic. If you obtain the FSM, you can use a scan tool and an ordinary volt ohmmeter to test for continuity and voltage drops along the identified circuits until the fault is found. A wiring fault (high resistance) can cause the codes to set and so it is only after the wiring is thoroughly checked that you start to consider a component malfunction. Most faults are wiring related though. If you want the necessary diagnostic steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an ABS system - controller area network malfunction diagnostic and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.